Pole-zero analysis and wavelength scaling of carbon nanotube antennas

Abstract

Carbon nanotube (CN) antennas have applications in the THz electromagnetic spectrum. Nanotubes have a highly dispersive and frequency dependent conductivity model. In this article, we compare the poles and zeros in the input impedance of CN antennas at different lengths. We used model-based parameter estimation to approximate the input impedance of the antenna with a rational function in the complex frequency domain. Despite dispersive conductivity of CN, the imaginary part of the poles and zeros are respectively the integer multiples and odd multiples of the imaginary part of the first pole and zero. However, the real part of poles is almost constant, while the pattern was not observed for the real part of zeros. We also show that CN dipoles operating between 43 and 53 GHz are well matched if the source impedance is much higher than 50 ohms, and even higher than 12.9 kX. The fundamental resonances (f 0 ) of CN dipoles plotted versus their inverse-half-length (1/L) are linearly related, but the intercept of the fitted straight line is non-zero unlike that for perfect electric conductor (PEC) dipoles. This leads to non-linear variation in wavelength scaling of CN dipoles. The resonant CN antennas are relatively much shorter than PEC dipoles. K E Y W O R D S carbon nanotube, model-based parameter estimation, wavelength scaling Int J RF Microw Comput Aided Eng. 2017;27:e21103.

Dynamic Absorption Enhancement and Equivalent Resonant Circuit Modeling of Tunable Graphene-Metal Hybrid Antenna

“…The electronic band structure of graphene is the main reason for the extraordinary properties, i.e., better thermal coefficient, high mechanical strength, and excellent electrical properties. Graphene plasmonic properties are closely linked to its complex surface conductivity [10]. The tunability of graphene conductivity mainly depends on the Fermi energy, i.e., (chemical potential).…”

“…The typical simulation method is quite complicated and it will hardly validate the basic theory principle of resonant antenna functionalities. A model-based parametric estimation (MBPE) is conducted on high impedance graphene nanotube antenna (CNT) to analyze antenna performance [10]. The resonant circuit models need to be developed to extend the knowledge on graphene antennas and to validate the simulations results to reveal insight into the parametric functionality of graphene antenna along with the physical understanding of resonant properties.…”

Measurement of surface conductivity of graphene at W‐band

“…It has been used in the synthesis of various active devices including field effect transistors and modulators operating at 10‐20 KHz . It has also found application in nano‐antennas for communication in THz band either as a 2D or 1D material . Graphene placed close to metallic nano‐antennas can be used to modify their resonant frequency, radiation efficiency and radiation pattern .…”

“…3 It has also found application in nanoantennas for communication in THz band either as a 2D 4 or 1D material. 5,6 Graphene placed close to metallic nanoantennas can be used to modify their resonant frequency, radiation efficiency and radiation pattern. 7 A noncontact characterization of graphene surface impedance at micro and millimeter waves was presented by placing the monolayer graphene sample on a substrate consisting of quartz and foam in the cross sections of rectangular waveguides WR 28 and WR 90, respectively.…”

Equivalent Resonant Circuit Modeling of a Graphene-Based Bowtie Antenna

“…The regular simulation process is very intricate and can hardly demonstrate the theoretical principle of antenna resonant performance. Model-based parameter estimation (MBPE) [16] was used to analyze the carbon nanotube antenna with a high impedance [17], which still needs to do the large-size matrix calculation. To shed light on the parametric performance of the antenna, as well as the physical insight of antenna resonance property, the resonance circuit model for graphene-based antennas should be studied to deepen comprehension on such antennas.…”